This invention relates to grass cutting machines. Throughout this specification and claims, the term "grass cutting machine" is used to include domestic lawn mowers, grass cutting machines for cutting larger areas of grass such as sports fields and parkland as well as grass verge cutting equipment.
There are two main types of grass cutting machine currently in production namely (1) a machine including a cutting system rotatable about an axis which is substantially vertical relative to ground datum, and (2) a machine having a cylindrical cutting unit which includes a plurality of blades and which, in operation, is rotatable about an axis which is substantially parallel to ground datum, i.e. horizontal. Type (1) machines may be supported relative to ground datum by a cushion of air (commonly called a hover machine), by wheels (commonly called a wheeled rotary machine) or a combination thereof. A rear roller may also be used in order to produce a striped effect upon cut grass. Type (2) is normally supported on a combination of wheels and rollers. However, in one prior U.S. Pat. No. 4,738,086, there is described and claimed a type (2) machine which is supported on a cushion of air.
Collection of grass cut by any type of grass cutting machine is a problem confronting all design engineers in this field and, in our prior European Patent No. 0037971, B1 there is described and claimed a lawn mower of the type which in operation is supported by a cushion of air and has a knife rotatable about a vertical axis and a fan wheel rotatable about the same axis, the fan wheel and the knife being shrouded by a hood, the mower having a rim around the hood and the hood having one or more than one opening for air to the air cushion, characterized in that at least a part of the air stream to the fan wheel before reaching the fan wheel is used to pick up and transport grass, leaves and the like from the ground to a collecting chamber in the mower, the collecting chamber having means for separating grass from air.